1. Field of Invention
The present invention relates to a refrigerant system, and more particularly to an air heating, air conditioning and water heating system comprising a multi-communicative valve unit which is capable of providing air conditioning, heating and delivering hot water for a predetermined premises.
2. Description of Related Arts
Referring to FIG. 1 of the drawings, a conventional vapor-compression refrigeration system usually comprises a compressor 201, a condenser 202, a heat exchanger 203, and a four-way valve 200, and utilize circulating refrigerant as a medium to absorb and remove heat from a predetermined space. The four-way valve 200 has four ports (which are named port 1, port 2, port 3 and port 4 in FIG. 1), and when the vapor-compression refrigeration system is used for air conditioning, port 1 is communicated with port 2 only while port 3 is communicated with port 4 only. This means that refrigerant may enter the four-way valve from port 1 and leave from port 2 or vice versa. Similarly, refrigerant may also enter the four-way valve 200 from port 3 and leave from port 4, or vice versa.
Under this condition, refrigerant circulates in the refrigeration system in a state of saturated vapor and first enters the compressor 201. The compressor 201 is arranged to compress the refrigerant to a higher pressure, and usually to a higher temperature and the refrigerant becomes superheated vapor. The superheated vapor of the refrigerant is arranged to enter port 1 of the four-way valve 200 and leave from port 2 thereof. The refrigerant leaving the four-way valve 200 is then guided to flow into the condenser 202, where the superheated vapor of the refrigerant is then cooled by flowing through a coil or tubes, and cooling agent, such as air or water, is arranged to flow across the coil or the tubes. The refrigerant performs heat exchange with the water flowing in the condenser 202 and a predetermined amount of heat is ejected from the refrigerant. The superheated vapor of the refrigerant is then condensed to become saturated liquid state.
The saturated liquid of the refrigerant is then arranged to flow through an expansion valve 208 and a plurality of other functional valves and a filter dryer 206 and finally reaches the heat exchanger 203. When the refrigerant passes through the expansion valve 208, it undergoes an abrupt reduction in pressure and results in adiabatic flash evaporation. The temperature of the refrigerant is then substantially lowered and is guided to enter the heat exchanger 203. When the refrigerant has entered the heat exchanger 203, it is arranged to perform heat exchange with other heat exchange mediums, such as water, so as to absorb heat from that medium. The refrigerant is then evaporated and leaves the heat exchanger 203. The evaporated refrigerant is then guided to enter port 3 of the four-way valve 200 and is routed to leave the four-way valve 200 from port 4 thereof.
The conventional vapor-compression refrigeration system further comprises an expansion tank 212 connected between the four-way valve 200 and the compressor 201, wherein the refrigerant leaving the four-way valve 200 from port 4 is then guided to flow into the expansion tank 212. The refrigerant leaving the expansion tank 212 is then guided to flow back to the compressor 201 for performing another refrigeration cycle as mentioned above.
When the above mentioned conventional vapor-compression refrigeration system works as a heating system, the refrigerant basically flows in a reverse direction as compared to that mentioned above. In this situation, the four-way valve 200 is operated in such a manner that port 1 is communicated with port 3 while port 2 is communicated with port 4. Thus, the refrigerant leaving the compressor 201 is then arranged to pass through port 1 of the four-way valve 200 and leave the valve from port 3. The superheated vapor of the refrigerant enters the heat exchanger 203 and performs heat exchange with other heat exchange mediums, such as water. Heat is extracted from the refrigerant and the refrigerant becomes liquid state and is arranged to leave the heat exchanger 203. In other words, the heat exchanger 203 in fact works as a condenser for condensing the refrigerant.
The refrigerant is then arranged to flow through the expansion valve 208 and the plurality of other functional valves and the filter dryer 206 in a similar manner mentioned above, and eventually enters the condenser 202. Now, the condenser 202 acts as an evaporator and the refrigerant is arranged to perform heat exchange with other heat exchange mediums, and is arranged to absorb heat from that medium. The result is that the refrigerant is again evaporated and is guided to flow through port 2 and port 4 of the four-way valve 200. The refrigerant is then guided to flow into the expansion tank 212 and back to the compressor 201 for performing another heating cycle.
There exist several disadvantages related to the above mentioned vapor compression refrigeration system. The refrigeration mentioned above has suffered from inefficient energy consumption and when it is installed in a building, it involves very expensive maintenance cost.
Second, the convention refrigeration system such as the one described above does not provide water heating function. As a result, a separate water heating system must be installed in the same building. An essential component of a water heating system is the boiler, which requires a lot of energy to operate (even in idle mode). Moreover, the installation of a separate water heating system requires separate designs and installations of the corresponding piping systems, ventilation systems and fire systems. Furthermore, the maintenance cost of such a separate water heating system is very expensive, and this is in addition to the maintenance cost of the conventional refrigeration system described above.